1. Field of the Invention
The present invention relates to a communications node name retrieving technique for identifying respective communications nodes at communication source and destination, and for specifying the respective communications nodes with network addresses in a computer network system such as the Internet, etc.
2. Description of the Related Art
In a communication, a network address such as an IP address is information essential for specifying a communications node. The network address is an address that represents a network position assigned to a communications node. A network system delivers communication information to a destination by using a network address as a clue.
Here, a communications node or a node means a network device connected to a network, such as a device (host) which becomes an end point of a communication, a router relaying a communication between hosts, or the like.
As described above, a user who makes a communication must determine a node at a communication destination, and its network address prior to making the communication. A domain name server (see DNS, RFC1591, RFC1034, and RFC1035), which is a name service function used on the Internet, is one method implementing the above described function. With the DNS, a communication partner is specified according to an FQDN or a predefined record type, so that the network address of the communication partner can be obtained, or an FQDN can be obtained from a network address inversely. The FQDN is called a fully qualified domain name, and indicates a name that completely describes from a host name to a highest-order domain name in a format like “xxx.yyy.fujitsu.co.jp”. The DNS is a distributed database system. With this database system, information registered at a certain point is gradually reflected on the whole of the database. Therefore, in a DNS system, a delay exists when an information change is reflected on the whole of the system.